Pulverizer



Nov. 17, 1964 w. c. ROGERS 3,157,365

PULVERIZER Filed Dec. 4, 1962 2 Sheets-Sheet 1 INVENTOR. Wayne Cl. Rogers ,.l

Nov. 17, 1964 w. c. ROGERS PULVERIZER 2 Sheets-Sheet 2 Filed Dec. 4, 1962 INVENTOR. ZI/ayne C. Rogers @M H oney United States Patent 3,157,366 PULVERIZER Wayne C. Rogers, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Filed Deca 1962, Ser. No. 242,3llil 14 (Ilaims. (Cl. 241188) This invention relates to a pulverizer and, more particularly, to apparatus arranged to produce pulverized coal for burning in suspension.

In the construction of pulverizers, particularly those of the attrition type, wear in the parts takes place because of abrasive action. This is because various elements are subjected to the flow of air and pulverized material, most of which is carbon, but some of which consists of hard particles of impurities such as pyrites. ,The wearing of pulverizer parts makes the pulverizer action less effective, so that the pulverizer must be shut down from time to time for the replacement of worn parts. As with any large piece of capital equipment, the occurrence of long periods when the apparatus is not available for use presents a considerable problem in connection with the overall plant operation. These and other diffi culti s which have been experienced with the prior art devices have been obviated in a novel manner by the present invention.

it is, therefore, an outstanding object of the invention to provide a pulverizer in which the wear of parts is reduced to a minimum and the necessity for shutdown for replacement of parts has been minimized.

Another object of this invention is the provision of an attrition-type pulverizer having stationary pegs with hardened inserts in which operative life has been considerably improved.

A further object of the present invention is the provision of an attrition-type pulverizer in which peg wear lates have an extremely long life.

It is another object of the instant invention to provide an attrition-type pulverizer in which the flow of air and of semi-pulverized solid fuel is improved.

With these and other objects in view, as will be ap parent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a vertical sectional view of a pulverizer embodying the principles of the present invention,

FIG. 2 is a perspective view of a stationary peg used in the pulverizer, 1

PEG. 3 is another perspective view as observed in the opposite direction of the peg.

FIG. 4 is a perspective view of a wear plate,

PEG. 5 is a perspective view of a peripheral liner, and

H68. 6 and 7 are perspective views of an element of the peripheral liner shown in FIG. 5 taken from two opposed directions.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the pulverizer, indicated generally by the reference numeral fit, is shown as being of the attrition type in which pulverization of solid material talzes place by the aerodynamic rubbing of one particle on another while in an air suspension. The pulverizer is provided with a generally tubular housing 11 consisting of three sections, a crusher housing 12, a grinding housing 13, and a fan housing 14. Extending through the housing 11 coaxially thereof is a shaft 15 mounted at one end in a bearing 16 fastened on the top of a pedestal 17 and, at the other end, in a bearing 18 bolted to a pedestal 19. The housing 11, the pedestal l7, and the pedestal l9 are all mounted on a base 21.

EJ571566 Patented Nov. 17, 1964 The crusher housing 12 is provided with an outer radial wall 22 and an inner radial wall 23. The inner wall 23 is provided with an opening 24 at the lower portion. In the upper part of the housing 12 is an inlet opening 25.

A hub 26 is keyed to the shaft 15 and locked in place against longitudinal movement therealong. Bolted to the hub are radially-extending support plates 27 on which are mounted swing hammers 2.8 of the type shown and described in the patent of Rogers No. 2,647,695. Underlying the hammers and extending from the front wall 22 to the rear wall 23 is a grid 2f having openings adequate to pass a desired size of crushed coal.

The grinding housing 13 is provided with a peripheral wall 31 and a rear wall 32, while it shares the wall 23 with the crusher housing 12. Fixed to the shaft 15 in the grinding housing is a hub 33 on which is mounted a circular radial plate 34. The side of this plate facing toward the wall 23 and toward the crusher housing 12 is provided with carbide-covered grinding pegs 35 extending parallel to the axis of the shaft 15 and with air circulating blades 36 for promoting some of the desired air flow through the passages. The pegs 35 and the blades 36 are locked in place and protected by wear plates 37. In a similar way, the side of the plate 34 facing toward the wall 32 is provided with wear plates 38 in which are mounted movable pegs 39. The pegs 34 and 39 are located close to the periphery of the plate 34. The surface of the wall 32. facing toward the plate 34 is provided with wear plates 49 in which are mounted stationary pegs 51. These pegs are mounted in a circle concentric with the axis of the shaft 15 and spaced slightly inwardly of the movable pegs 39. Mounted around the inner surface of the peripheral wall 31 are peripheral liners 42.

The wall 32 is provided with a circular exit opening which is coaxial of the shaft 15 and which is provided with a protecting ring 44. Extending outwardly from the hub 33 but spaced longitudinally of the plate 34 are a series of rejector arms suitably provided with carbide inserts in the manner shown and described in the patent of Rogers No. 2,625,332.

The fan housing 14 is provided with an outer peripheral wall do and a radial wall 47 and it shares the wall 32 with the grinding housing 13. The fan housing 14 is provided with an outlet opening (not shown but in the conventional manner) and is provided with a ceramic liner 48. Mounted on the shaft 15 on the portion which ies within the fan housing 14 is a hub 49 on which is mounted a circular plate 51 having on the surface facing toward the wall 32 near its outer periphery a number of fan blades 52. The surface of the plate 51 facing toward the wall 47 is provided with backing angles 53 to counteract the bending forces produced by centrifugal action on the blades 52 during rotation.

Referring now to FIGS. 2 and 3, which show more specifically the construction of the stationary pegs 41, it can be seen that each peg consists of a circular base 54 from the center portion of which extends an arm 55. The main portion of the arm has a somewhat oval crosssection and a flat surface 56 on which are mounted three thin blocks 57, 58, and S of carbide. At the outer end of the arm it is provided with a generally rectangular portion 61 which is considerably wider than the arm 55 and which also has a fiat face 62 constituting an extension of the flat surface 56 of the arm. On the face 62 is mounted an inner block 63 of carbide and an outer block 64 of carbide, the latter block having an outer flat surface 65 which is inclined at a substantial angle to the general direction of the arm 55 and to the face surfaces of the other carbide blocks 57, 58, 59, and 63. The block 64 is, therefore, thicker at the outer edge than it is at the inner edge; and it tapers to a thickness equal to the block as along the edge where it contacts that block.

Extending upwardly from the base 54- is an abutment 66 which is somewhat semi-circular in plan view and presents a straight plane surface 67 which lies snugly against the outer face of the carbide block 57. The base is also provided with a thin radial flange 68 and a finger 69 which are used to lock the stationary peg 41 in the wear plate 49.

FIG. 4 shows the details of the wear plate 33. As is evident in the drawing, the overall plate is somewhat segmental in form so that a series of these can be arranged and fitted closely together around the periphery of the plate 34. Entering one radial edge is a notch 71 which carries the peg 39. Part of the notch which opens on the outer face 72 of the plate has a semi-circular surface 73 which lies against a corresponding cylindrical surface of the peg 39. Extending away from this recess '73 radially of the shaft 15 is a slot 74 in which is mounted a carbide block 75, the block having a curved edge that blends with the cylindrical surface of the recess 73.

FIGS. 5, 6, and 7 show the details of the peripheral liner 42. The liner consists of a main body 76 having replaceable grinding elements 77, 78, and 79. Along one side of the body are arranged a series 81 of serrations molded into the material of the main body. A similar series 82 is arranged parallel to the series 81 there being an area St) between the two series which is free of serrations. This area, as is evident in FIG. 1, lies adjacent the periphery of the plate 34, the series 81 being arranged along the entrance side and the series 32 arranged around the exit side of this plate. The elements 77, 78, and 79 are locked to the main body in the same manner. For instance, the element 77 consists of a cast iron block 83 having a flat face Sgt on which are mounted three thin tungsten carbide blocks 85. The back of the block 83 is provided with a generally cylindrical abutment 86 which fits snugly in a groove 87 formed on the surface of the serration to which the element 77 is attached. As is evident in FIG. 1, the abutment 86 is provided with a threaded bore and the main body 76 is provided with an aperture, so that a bolt 88 may be used to hold the element 77 in place and to permit its removal, when desired.

The operation of the apparatus will now be readily understood in view of the above description. Fuel and air enter the pulverizer 10 through the entrance opening 25 in the crusher housing 12. The material to be pulverized is contacted by the hammers 28 and, when reduced in size to a sutficient degree, passes through the grid 29. Air flowing through the pulverizer carries the crushed coal into the grinding housing 13 where it first comes in contact with the blades 36 which assist the air and fuel in moving outwardly under centrifugal action and the force of air flow. The fuel is given a primary grinding by the aerodynamic action of the pegs 35 and the series 31 of serrations on the peripheral liner 42. The fuel then passes across the passage 80 and then comes into the area between the series 82 of serrations of the peripheral liner and the movable pegs 39. The fuel and air pass radially inwardly across the stationary pegs 41 and then flow axially through the exit opening 43, Some of the coarse material is thrown back by the rejector arms 45 for regrinding. Eventually, the fines come under the influence of the fan blades 52 and leave the pulverizer for consumption in the steam generating unit or the like.

Because of the recirculation of material to be pulverized from the rejector arms 45 back to the peripheral liner 42, and the reversal for movement through the pegs 39 and 41 again close to the disk 34, the serrations of the peripheral liner are subjected to considerable abrasive action. For that reason, the presence of the elements 77, 78, and 79 and their carbide blocks 85 remove a source of considerable wear in the pulverizer. At the same time, the return of the coarse particles along the plate 40 close to the base of the peg 41 presents considerable abrasive action to the shank of the peg. The

outer end is Well taken care of by the blocks 63 and 64 of carbide and the inner shank which is subjected to the recirculation action from the rejector arms are protected by the blocks 57, 58, and 59. Because of the aerodynamic action around the base of the peg, the edge of the block 57 where it lies along the hub of the peg is a location of cutting action which, eventually, cuts the peg in two. The smooth semi-circular abutment 66, however, protects this area and causes the air and abrasive particles to move around the peg and to have little effect in wearing at the base.

The abrasive particles moving radially inwardly along the cheek plate 38 tend to produce a cutting action in the slight spacing between the base of the movable peg 39 and the recess 73 of the cheek plate 38. Once a narrow groove has been ground between these two elements, then a considerable swirling effect takes place in that area and abrasive action then takes place very rapidly. The presence of the carbide insert prevents such a passage from ever developing. The carbide block continues to act as a gateway across any path which the abrasive materials attempt to cut, so that a source of considerable difficulty is removed.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent, 1s:

1. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(0) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof, each peg having a base,

(a') stationary pegs extending parallel to the axis from an end plate toward the movable pegs,

(e) a wear plate fastened to the rotor plate surrounding each movable peg, the wear plate having a socket in which the base of the peg fits snugly, and

(f) a block of extremely hard material fastened in the wear plate with an edge which forms a portion of the surface of the socket in an area where extreme wear normally takes place.

2. An attrition pulverizer as recited in claim 1, wherein the said block of extremely hard material is generally elongated and extends from the socket radially toward the axis of the shaft.

3. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(c) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof,

(d) stationary pegs extending parallel to the axis from an end plate toward the movable pegs, each stationary peg consisting of a base and an arm extending from the base, the arm having a flat surface which extends radially and axially and which is covered with blocks of extremely hard material, the outermost block having a plain face surface which extends at a substantial angle to the said fiat surface,

(e) a wear plate fastened to the rotor plate surrounding each movable peg, the wear plate having a socket in which the base of the peg fits snugly, and

(f) a block of extremely hard material fastened in the wear plate with an edge which forms a portion of the surface of the socket in an area where extreme wear normally takes place.

4. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(0) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof, each peg having a base,

(d) stationary pegs extending parallel to the axis from an end plate toward the movable pegs,

(e) a wear plate fastened to the rotor plate surrounding each movable peg, the wear plate having a socket inwhich the base of the peg fits snugly,

(f) a block of extremely hard material fastened in the wear plate with an edge which forms a portion of the surface of the socket in an area where extreme wear normally takes place, and

(g) peripheral liners fastened to the inner surface of the tubular housing and extending axially on either side of the rotor plate, a row of serrations being formed on each liner on either side of the rotor plate, there being a portion of the liner which is free of serrations in the vicinity of the rotor plate.

5. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(0) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof,

(d) stationary pegs extending parallel to the axis from an end plate toward the movable pegs, each stationary peg consisting of a base and an arm extending from the base, the arm having a flat surface which extends radially and axially and which is covered with blocks of extremely hard material, the outermost block having a plain face surface which extends at a substantial angle to the said flat surface, and

(e) peripheral liners fastened to the inner surface of the tubular housing and extending axially on either side of the rotor plate, a row of serrations being formed on each liner on either side of the rotor plate, there being a portion of the liner which is free of serrations in the vicinity of the rotor plate.

6. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(0) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof,

(0.) stationary pegs extending parallel to the axis from an end plate toward the movable pegs, each stationary peg consisting of a base and an arm extending from the base, the arm having a hat surface which extends radially and axially and which is covered with extremely hard material, the outermost end of the arm having a plain face surface which extends at a substantial angle to the said fiat surface,

(e) a wear plate fastened to the rotor plate surrounding each movable peg, the wear plate having a socket in which a base of the peg fits snugly,

(f) a block of extremely hard material fastened in the wear plate with an edge which forms a portion of the surface of the socket in an area where extreme wear normally takes place, and

(g) peripheral liners fastened to the inner surface of the tubular housing and extending axially on either side of the rotor plate, a row of serrations being formed on each liner on either side of the rotor plate, there being a portion of the liner which is free of serrations in the vicinity of the rotor plate.

7. An attrition pulverizer as recited in claim 6, wherein the base of each stationary peg is providedwith a substantial abutment which extends in the same direction as the arm and which has a flat surface that extends close to and coextensive with the block closest to the base.

8. An attrition pulverizer as recited in claim 6, wherein the arm of each stationary peg consists of a relatively narrow portion adjacent the base and a relatively wide portion at the outer end, the wide portion being coextensive with a portion of the movable pegs.

9. An attrition pulverizer as recited in claim 6, wherein the arm of each stationary peg consists of a relatively narrow portion of oval cross-sectional form terminating in the said fiat surface and of a head at the outer end, the head being substantially wider than the narrow portion and having a plain back surface opposite the said flat surface inclined to and merging with the oval form of the narrow portion.

10. An attrition pulverizer as recited in claim 6, wherein the said block of extremely hardened material in the wear plate is generally elongated and extends from the socket radially toward the axis of the shaft.

ll. An attrition pulverizer as recited in claim 6, wherein the serrations present plain surfaces that extend generally radially and face in opposition to the movement of the rotor plate.

12. An attrition pulverizer as recited in claim 6, wherein the serrations on one side of the rotor plate are provided with protective elements, each protective element having a plain surface which lies against a corresponding surface of its respective serration and having a key which engages a similarly-formed socket on the serration, each protective element having a plain surface parallel to the aboverecited surface on which is mounted an extremely hard material.

13. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(1)) a shaft extending axially of the housing and carrying a radial rotor plate,

(c) movable pegs extending parallel to the axis from p the plate adjacent the periphery thereof,

(d) stationary pegs extending parallel to the axis from an end plate toward the movable pegs, and

(e) peripheral liners fastened to the inner surface of the tubular housing, and extending axially on either side of the rotor plate, a row of serrations being formed on each liner on either side of the rotor plate, there being a portion of the liner which is free of serrations in the vicinity of the rotor plate, the serrations presenting plane surfaces that extend generally radially and which face in opposition to the movement of the motor plate.

14. An attrition pulverizer, comprising (a) a tubular housing having radial end plates,

(b) a shaft extending axially of the housing and carrying a radial rotor plate,

(0) movable pegs extending parallel to the axis from the plate adjacent the periphery thereof,

(d) stationary pegs extending parallel to the axis from an end plate toward the movable pegs, and

(e) peripheral liners fastened to the inner surface of the tubular housing, and extending axially on either side of the rotor plate, a row of serrations being formed on each liner on either side of the rotor plate, there being a portion of the liner which is free of serrations in the vicinity of the rotor plate, the serrations on one side of the rotor plate being provided with protective elements, each protective element having a plane surface which lies against a corresponding surface of its respective serration and having a key which engages a similarly-formed socket on the serration, each protective element having a plane surface parallel to the above-recited surface on which is mounted an extremely hard material.

References Qited in the file of this patent UNITED STATES PATENTS 1,212,418 turtevant Jan. 16, 1917 1,840,380 Andrews Ian. 12, 1932 2,628,038 Rogers et a1. Feb. 10, 1953 

1. AN ATTRITION PULVERIZER, COMPRISING (A) A TUBULAR HOUSING HAVING RADIAL END PLATES, (B) A SHAFT EXTENDING AXIALLY OF THE HOUSING AND CARRYING A RADIAL ROTOR PLATE, (C) MOVABLE PEGS EXTENDING PARALLEL TO THE AXIS FROM THE PLATE ADJACENT THE PERIPHERY THEREOF, EACH PEG HAVING A BASE, (D) STATIONARY PEGS EXTENDING PARALLEL TO THE AXIS FROM AN END PLATE TOWARD MOVABLE PEGS, (E) A WEAR PLATE FASTENED TO THE ROTOR PLATE SURROUNDING EACH MOVABLE PEG, THE WEAR PLATE HAVING A SOCKET IN WHICH THE BASE OF THE PEG FITS SNUGLY, AND (F) A BLOCK OF EXTREMELY HARD MATERIAL FASTENED IN THE WEAR PLATE WITH AN EDGE WHICH FORMS A PORTION 